Process of electrodepositing an alloy of lead and indium



Patented Sept. 18, 1951 PROCESS OF ELECTRODEPOSITING AN ALLOY OF LEAD AND INDIUM DavidFrederick Green, lq oel Percy Mallet, and James McKenzie Briscoe, London, England, assignors to Vandervell Products Limited, London, England A No Drawing. Application'December 13, 1946, Se-- rial No. 716,180. .In Great Britain December 2 Claims.

This invention relates to the electro-deposition of metals. The particularobject of the invention is to provide a method whereby a layer of a metallic alloy comprising lead and indium, with or without other constituents, can be deposited electrolytically to form the bearing metal layer of a bearing for internal combustion engines or other devices. The method of the invention may, however, be applied to the electro-deposition of other metals and metallic alloys and may be used for purposes other than the production of bearings.

The invention consists broadly in the use as the electrolyte or bath in the electrolytic process of a solution of the perchlorates of the metal or metals to be deposited. The electrolyte may consist of the perchlorates dissolved in water, but preferably these perchlorates 'are dissolved in an organic solvent to which, however, water may be added, in some circumstances.

Satisfactory results have been obtained by the use as the ionising solvent of a substantially an- (Cl. 204 4s anode current density of '7 to amperes per hydrous ether derivative of ethylene glycol of the type R.O. (CH2)2.OH where R represents an alkyl' group. I

A solvent of this type with which we have obtained satisfactory results in practice is ethoxyethyl alcohol, which is available commercially under the name of ethyl cellosolve. The same solvents may also be used with water present and, as before indicated, it may be desired in some cases to employ an electrolyte comprising the aqueous solutions of the respective perchlorates without the addition of organic solvents. When the aqueous electrolytes are employed, it is nec: essary to have some free perchloric acid present, at least sufiicient to prevent precipitation of the metals to be deposited in the form of .substantially insoluble compounds, and also to control anode dissolution. The anode should where possible be of such a composition as to maintain the correct concentrations of metals in the electrolyte appropriate to the composition of the alloy being deposited at the cathode. The use or substances known as inhibitors or addition agents is in some cases advantageousinbringing about a substantial improvement in the nature of the deposit. 1

In order that the invention and the manner in which it is performed may be more clearly understood details are given below ofcertain spe- Example I I (Jo-deposition of an alloy of lead and indium was effected from an aqueous bath having the following composition:

Lead, 1 gm./l. as perchlorate.

Indium, 21 gm./l. as perchlorate.

Added perchloric acid, 20 gm./l., added as by weight aqueous solution.

The deposition was made at a cathode and square foot at room temperature and the deposit contained about 10% of lead by weight the remainder being about 90% indium. The deposit ,was light in colour and smooth. 1

Example II (lo-deposition of an alloy oi lead and indium was effected from a non-aqueous bath of the following composition:

Lead, gm./l. as perchlorate. Indium, 20 gm./l. as perchlorate. No added perchloric acid.

Ethoxyethyl alcohol as solvent.

Deposition was made at anode and cathode current densities of '7 to 10 amperes per square i'ootat a temperature of 60 C. The deposit was similar in nature to that obtained from the aqueous electrolyte of Example I, but contained a higher proportion of lead.

Example III A bearing metal layer of lead indium alloy was applied to the cylindrical surface of a main shaft bearing, such as is used in aircraft internal com-- bustion engines, in the following manner. The bearing consisting of a steel back with a lead bronze layer thereon, was machined to within the. fine limits usually encountered in practice,

- or the composition indicated below with a bath temperature between and 0.. verv 81mm agitation being employed in order that no local heating of the solution should take place:

Indium, 20 gm./1., lead, 11 gm./l., as perchlorates in ethyl cellosolve. Colophony, 4 gm./l.

A cathode current density of '7 to amps. per square foot was used. The deposit obtained was smooth in appearance and-contained approximately; 5%v indium with the balance sub-' o stantially lead. The bond between the deposit and the lead bronze layer was excellent and this is regarded as arising from the fact that the electrolyte acts as a cleaner. The anode employed consists of an 8% indium lead alloy and showed satisfactory dissolution. From' the foregoing it will be seen that the'indium -lead l alloy anode had a slightly higher percentage ofindium than that present in the deposit. The

cathode efliciency was of the order-;of. 70%;. go...

In effecting the co-deposition-of leadindium alloys by the method illustrated by the fore going examples, the composition of the deposit obtained is dependent upon a number of factors;

including temperature, the degree of agitation used. (increased agitation markedly increasing theaxlead concentration in the deposit) and the metal"v ion concentrations. The following table shows the approximate effect on the composition of the deposit of varyingthe lead concentration 80 between 5 and 12 grams per liter in the solution-used in- Example III above, all'other factors being 'as' nearly as possible unchanged:

Pb concentrationgm/l 5 6 7" Per Cent indium in depositiu. 20 15 Qwing'tothe difiiculty of ensuringsimilar conditions-in all tests these figuresf-shouldfwbe regarded as showing only the general effect: of varyingthe lead concentration and not as.a'= precise; guide to the lead concentration; required to produce a deposit of given composition. We

in ethe non-aqueous solvents."

An increase in temperature iresultsin an:in:-; crease in the conductivity of the bath and if electrolysis is carried. but at higher temperature it is desirable or. necessary. to decreasethevoltage applied .to the. cell in order to maintain. the

current dehsit'yin the range prescribed...

Another specific application of theinvention. islts-use 'fo'r. efiectingthe electro-deposition of a trnaryalloy comprising lead, tin-and'indium-u for the. purpose of providing a bearing: surface 7 layer... The-percentage composition ,of the=-.ma-.

terialdeposited will vary withithe particulam application, of the bearing layer.

The specificationnf co-pending application. fora letters Patent No.=.' 7 08'-,190 filed November -6,-- 1946;.1

by Guy Anthony Vandervell and Noel Percy Mallet, which has become abandoned, describes (inter alia) a hearing which comprises a steel back, an intermediate layer of lead bronze and a final bearing layer of lead, indium and tin. In such bearings it is inadvisable to have a final layer containing much tin, as thin tin is apt to diffuse thermally from the upper layer into the I SllbStIB-tlir I onlthe' other hand, when the bearingdayer is deposited directly on to a steel back in the manner- -described in co-pending application for Letters Patent-No.-669,448 of David Frederick Green, John Ernest-Salmon and Noel Percy Mallet filed May 13, 1946, we prefer to deposit an alloy containing a=substantially;greater proportion of tin. Such 'higher-tin content alloys may also be used in 'mult i ply ibearings in cases where the thermal diffusion"of"tin' into the bronze intermediate layer is notwa :prohibitive factor, for example,

whenlead is absentafrom the bronze.

Efample IV Thefollowing alloy was deposited directly on to a steel back from our electrolytic bath, the analysisbeing ofa nominal nature' ascsome- 11m purities are *irfevltably present'z Per centsa 42ft" A v 42*? Indium --16 The electrolyte iused-sin xdepositing this alloys" was 1 prepared from the perchloratesofw lead; and in'diumri dissolvedinc:ethoxyethylg alcohol.

The. el'ectrolyte was :initiallyi'substantially ;.-anhy-=;

drous and had-sthel followin'gicomposition t Y Indium"; Colophonyj The bath was operated at -0., without \any-., agitationx Cathode-current: density=anode-current 'aderisity=l0" .amps. per square foot. Lead indiumc alloy-:anodes-s'containing :-10% .by weightof indium were used. We have; however; found... that by suitable adjustment of the anode compo-s; sition a -amate'rial comprising :4 all three metals mayiibeaemplo'yed; for instance an I anode .iOOHhtainin'g -60%1e&d f 20%il1dil1flfr3l'ld' 20 %";:ti-n dis-w solvesat the theoretical-rate Whatiweclaim and desi're to secure by Letters,

55 Patentis::

1. A' processrof electro depositingsan alloysofa: lead-'and'i'in'dium whmh comprises-=1 the "stepseo r1 preparing.aaiinoneaqueous solutionof about:2

grams: per liter'cof cindium: asvperchlorateuand 11".: to -12i tgrains p'errliter of lead asrperchlorate -=dis-,:;-; solved in ethoXyet-hyl alcohol; ;passi-ng ;a current through thei .electrodesr'while maintaining: theatcathodetcurrent densityrat about. '7'to l0 amperes per-1* squarefoot, the alloy; electro-depositedg rangingufrom 90 to*1%x:indium and thewbalanc 1e lead, ,the' anode :conta-lningqanalloy 1 of lead and: indiummwith'slightly higher percentage of: -in.--

diumthan in the deposit andimaintain-ing: the r;

bath temperature 1 from 60- to C.

lead and indium which comprises the steps. oipreparing a non-aqueous solution of about '20 grams per liter-of indium as perchlorate andaii to -l2 -grams per liter of lead as= perchlorate dis-.;- ,solved 1n-ethoxyethi lealcohol,.passingaa currents 2.- A process -of electro-depositingqan 'alloy ofr.

through the electrodes While maintaining the current density at about 7 to 10 ampres per square foot, the alloyelectro-deposited ranging from 40 to 1% indium and the balance lead but in inverse proportion to the concentration of lead perchlorate, the anode containing an alloy of lead and indium with slightly higher percentage of indium than in the deposit and maintaining the bath. temperature from 60 to 80 C.

DAVID FREDERICK GREEN.

NOEL PERCY MALLET.

JAMES MCKENZIE BRISCOE.

REFERENCES CITED The following references are of record in the file of this patent:

OTHER REFERENCES Chaney et al.: Journal of Physical Chemistry,

i0 V01. 35, pp. 2294, 2295, 2306, 2310-2313 (1931).

Mathers et al.: Transactions American Electrochemical Society, vol. 26, pp. 133-135 (1914).

Handbook of Chemistry and Physics, 26th edition, page 1360 (1942-1943). 

1. A PROCESS OF ELECTRO-DEPOSITING AN ALLOY OF LEAD AND INDIUM WHICH COMPRISES THE STEPS OF PREPARING A NON-AQUEOUS SOLUTION OF ABOUT 20 GRAMS PER LITER OF INDIUM AS PERCHLORATE AND 1 TO 12 GRAMS PER LITER OF LEAD AS PERCHLORATE DISSOLVED IN ETHOXYETHYL ALCOHOL, PASSING A CURRENT THROUGH THE ELECTRODES WHILE MAINTAINING THE CATHODE CURRENT DENSITY AT ABOUT 7 TO 10 AMPERES PER SQUARE FOOT, THE ALLOY ELECTRO-DEPOSITED RANGING FROM 90 TO 1% INDIUM AND THE BALANCE LEAD, THE ANODE CONTAINING AN ALLOY OF LEAD AND INDIUM WITH SLIGHTLY HIGHER PERCENTAGE OF INDIUM THAN IN THE DEPOSIT AND MAINTAINING THE BATH TEMPERATURE FROM 60 TO 80* C. 